1. Field of the Invention
The present invention relates to a laser ablation process for preparing a superconducting thin film and an apparatus for executing such a process, and more specifically to a laser ablation process for preparing a superconducting thin film formed of a compound oxide superconductor material, and an apparatus for executing the process.
2. Description of Related Art
A superconducting phenomenon is used to be though as a phenomenon which occurs at extremely low temperature which is realized by liquid helium cooling. However, Bednorz and Muller et al discovered [La,Ba].sub.2 CuO.sub.4 compound oxide superconductor which is superconducting at a temperature of 30K in 1986, Chu et al discovered Y.sub.1 Ba.sub.2 Cu.sub.3 O.sub.7-.delta. compound oxide superconductor of which the critical temperature T.sub.c is in the range of 90K in 1987, Maeda et al discovered compound oxide superconductors of so called Bi family of which the critical temperature T.sub.c is higher than 100K in 1988. Since these high-T.sub.c copper-oxide type compound oxide superconductors are superconducting by cheep liquid nitrogen cooling, practical applications of superconducting phenomena have been studied by many researchers.
At the beginning, these compound oxide superconductors were prepared as sintered material which were synthesized by solid phase reactions. In these days, the studies have progressed so that extremely high quality compound oxide superconductor thin films have been prepared.
In the prior art, a compound oxide superconductor thin film is deposited on a substrate at substrate temperatures over 700.degree. C. by a laser ablation process which is one of the most suitable process for preparing a compound oxide superconductor thin film. This high substrate temperature causes diffusion of constituent atoms into the depositing compound oxide superconductor thin film. The diffusion of the constituent atoms of the substrate may deteriorate properties of a compound oxide superconductor thin film considerably.